This invention relates to a wood preservative composition comprising a biocidally effective amount of at least one amine oxide and a method of controlling microorganisms in a wood substrate or other cellulosic or fiber material with the wood preservative composition. This invention also relates to a method of removing algae from a substrate with one or more amine oxides.
Wood is an important building and construction material that is used in a variety of applications, such as housing material, utility poles, and railroad ties. Effective wood preservatives and waterproofing compounds that improve dimensional stability are necessary to maintain the integrity of these structures.
Quaternary alkyl ammonium compounds (QAC""s), such as didecyldimethylammonium chloride (DDAC), have been shown to be effective as fungicides. However, QAC""s do not readily penetrate and uniformly distribute into wood. Because of the poor penetration and distribution, certain areas of the wood do not receive adequate protection, often resulting in the wood rotting from the inside out. Furthermore, DDAC corrodes steel tanks and other metal components commonly used in wood treatment systems.
U.S. Pat. No. 4,357,163 discloses a chlorinated phenol wood treating composition containing a chlorophenol, a fatty acid amine oxide, and water. The amine oxide was included to increase penetration of the chelating agents and chlorophenols into the wood and to stabilize the chlorophenol in water.
U.S. Pat. No. 5,833,741 discloses a waterproofer wood preservative system comprising a waterproofing enhancing amount of waterproofer composition and a biocidally effective amount of a biocide. The waterproofer is an alkyl dimethyl amine oxide, an alkyl acetoacetate, or a waterproofing quaternary ammonium compound. The biocide comprises at least one biocidal quaternary ammonium compound. Generally, the concentration of biocide in the waterproofer wood preservative system is 0.25 to 4% by weight.
U.S. Pat. Nos. 3,296,145 and 3,484,523 disclose a composition for cleaning, softening, and sanitizing fabrics; cleaning and sanitizing walls and floors; and cleaning and degerming human skin and similar organic tissue. The composition contains a quaternary alkyl ammonium compound and a tertiary amine oxide.
U.S. Pat. No. 4,179,504 discloses alkyl amine oxides which are effective as ectoparasiticidal and ovicidal toxicants and their use in shampoos.
Devinsky et al., Chemical Abstracts 103:122986s (1 986), disclose certain N,Nxe2x80x2-didecyl-N,Nxe2x80x2-dimethyl-xcex1,xcfx89-alkanediamine dioxides which inhibit the growth of bacteria and fungi.
Societe de Produits Chimiques et de Synthese, Chemical Abstracts 84849c (1966), discloses that dimethyl-laurylamine oxide, bis(xcex2-hydroxyethyl)laurylamine oxide, and dimethylsoyaamine oxide were used for suppressing the growth of some dermal fungi or bacteria, such as C. perfringens, S. anaerobius, and A. niger. 
However, prior to the present invention, there was no indication that amine oxides would be effective as wood preservatives. In fact, their inclusion in wood treating solutions was to either stabilize a preservative ingredient, such as chlorophenol as in U.S. Pat. No. 4,357,163, or act as a waterproofer in conjunction with a preservative ingredient, as in U.S. Pat. No. 5,833,741.
In light of the foregoing, it is desirable to have a wood preservative that has broad antifungal activity, low toxicity to non-target organisms, high phase stability in water, and low corrosivity.
The present inventors have discovered that amine oxides are highly effective as wood preservatives. The present invention provides a wood preservative composition comprising a biocidally effective amount of one or more amine oxides. Preferably, the wood preservative composition is substantially free of halogenated compounds (such as halides and chlorinated compounds) and quaternary ammonium compounds. The wood preservative composition of the present invention exhibits low toxicity, high stability in water, low corrosivity to metal substrates (such as steel substrates), excellent penetration and uniform distribution into wood, low odor, waterproofing properties, and high leaching resistance. The wood preservative composition may be applied to the surface of a wood substrate or be applied by pressure treating the wood substrate with the wood preservative composition. Other cellulosic and fiber materials, such as cotton, burlap, and like materials, may also be preserved with the composition of the present invention.
Another embodiment is a method of controlling microorganisms, such as fungal decay organisms (generally known as white rot, brown rot, and soft rot fungi) and sapstain organisms (e.g. stains, mold, and fungi) on and/or in a wood substrate, such as fresh cut lumber, comprising applying a biocidally effective amount of the composition of the present invention to the wood substrate.
Yet another embodiment is a method of controlling sapstain organisms and/or fungi (including mold) on and/or in a wood substrate, such as fresh cut lumber, comprising applying a sapstain and/or fungicidally (mold) inhibiting effective amount of one or more amine oxides and one or more phosphonic iron stain inhibitors.
Yet another embodiment of the present invention is a wood preservative system comprising a wood substrate and a biocidally effective amount of one or more amine oxides. Preferably, the wood substrate comprises a fungicidally or sapstain inhibiting effective amount of one or more amine oxides.
The present invention provides a wood preservative composition comprising a biocidally effective amount of one or more amine oxides. The composition of the present invention exhibits high penetration and uniform distribution into wood substrates as well as low corrosivity to metal substrates and high leaching resistance.
The amine oxide may be a trialkylamine oxide, an alkylcyclicamine oxide, a dialkylpiperazine di-N-oxide, an alkyldi(poly(oxyalkylene))amine oxide, a dialkylbenzylamine oxide, a fatty acylamidopropyldimethylamine oxide, a diamine dioxide; a triamine trioxide, or any combination of any of the foregoing.
Preferred trialkylamine oxides have the formula R1R2R3Nxe2x86x92O, where R1 is a linear, branched, cyclic or any combination thereof C8 to C40 saturated or unsaturated group; and R2 and R3 independently are linear, branched, or any combination thereof C1 to C40 saturated or unsaturated groups. R1, R2, and R3 independently may be alkyl, alkenyl, or alkynyl groups. More preferably, R1 is a linear, branched, cyclic or any combination thereof C8 to C22 saturated or unsaturated group, such as coco, hydrogenated tallow, soya, decyl, and hexadecyl; and R2 and R3 independently are linear, branched, or any combination thereof C1 to C22 saturated or unsaturated groups, such as coco, hydrogenated tallow (which is typically about 70-75% by weight of C18 alkyl, about 20-25% by weight of C16 alkyl, and traces of lower derivatives), soya, decyl, and hexadecyl.
A preferred trialkylamine oxide is a dialkylmethylamine oxide having the formula R1R2CH3Nxe2x86x92O, where R1 and R2 are defined as above. Another preferred trialkylamine oxide is an alkyldimethylamine oxide having the formula R1(CH3)2Nxe2x86x92O, where R1 is defined as above. More preferred alkyldimethylamine oxides have the formula R19(CH3)2Nxe2x86x92O, where R19 is a linear or branched C8-C18 alkyl. Preferably, R19 is a linear or branched C10-C16 alkyl. Alkyldimethylamine oxides are non-toxic and non-mutagenic surfactants. Suitable alkyldimethylamine oxides include, but are not limited to, decyldimethylamine oxide, cocodimethylamine oxide, dodecyldimethylamine oxide, a C10-C14 alkyldimethylamine oxide, hexadecyldimethylamine oxide, a C16-C18 alkyldimethylamine oxide, and any combination of any of the foregoing. A more preferred wood preservative composition contains a mixture of dodecyl dimethyl amine oxide and hexadecyl dimethyl amine oxide.
Preferred alkylcyclicamine oxides have the formula R4R5R6Nxe2x86x92O where R4 is defined as R1 above and R5 and R6 are linked to form a cyclic group. The cyclic group typically contains from 4 to 10 carbon atoms and may optionally contain oxygen, sulfur, nitrogen, or any combination of any of the foregoing. More preferred alkylcyclicamine oxides include, but are not limited to, an alkylmorpholine N-oxide, a dialkylpiperazine di-N-oxide, and any combination of any of the foregoing.
Preferred alkylmorpholine N-oxides have the formula 
where R7 is defined as R1 above. According to a more preferred embodiment, R7 is a linear or branched C10 to C16 alkyl. Examples of preferred alkylmorpholine N-oxides include, but are not limited to, cetyl morpholine N-oxide and lauryl morpholine N-oxide.
Preferred dialkylpiperazine di-N-oxides have the formula 
where R8 is defined as R1 above and R9 is defined as R2 above.
Preferred alkyldi(poly(oxyalkylene))amine oxides have the formula 
where R10 is defined as R1 above; R11 and R12 independently are H or CH3; and m and n independently are integers from about 0 to about 10 and at least one of m and n is greater than 0.
Preferred dialkylbenzylamine oxides have the formula R13R14R15Nxe2x86x92O, where R13 is defined as R1 above; R14 is defined as R2 above; and R15 is benzyl. More preferred dialkylbenzylamine oxides include, but are not limited to, alkylbenzylmethylamine oxides having the formula R13R15CH3Nxe2x86x92O where R13 and R15 are defined as above. According to a more preferred embodiment, R13 is a linear or branched C8-C12 alkyl.
Preferred fatty acylamidopropyldimethylamine oxides have the formula 
where R16 is defined as R1 above.
Preferred diamine oxides have the formula 
where R17 is defined as R1 above; and m is an integer from about 1 to about 10.
Preferred triamine oxides have the formula 
where R18 is defined as R1 above; and m and n independently are integers from about 1 to about 10.
Long chain (C16 or greater) amine oxides, such as hexadecylamine oxides and hydrogenated tallow amine oxides, are particularly preferable for imparting waterproofing properties to the composition. Short chain (C14 and shorter) amine oxides aide are water soluble and aide in solubilizing long chain amine oxides and are typically better preservatives.
A blend of long chain and short chain amine oxides is contemplated in one embodiment of the present invention. The long chain amine oxides are generally blended with the short chain amine oxides at a weight ratio of from about 5:1 to about 1:5 and preferably at a weight ratio of from about 2:1 to about 1:1.
According to a preferred embodiment, the composition contains a mixture of C16-C18 long chain amine oxides to impart waterproofing properties and C10-C14 short chain amine oxides to solubilize the long chain amine oxides. A particularly preferable blend is a mixture of hexadecyldimethylamine oxide and dodecyldimethylamine oxide at a weight ratio of about 5:2.
The wood preservative composition comprises a biocidally effective amount of one or more amine oxides. Preferably, the composition comprises a fungicidally effective amount and more preferably a sapstain inhibiting effective amount of one or more amine oxides.
The wood preservative composition can be used to prevent the growth of sapstain (e.g. stains, mold, and fungi) on fresh cut timber between the time the timber is cut into board and the time when the board has dried to a low moisture content.
An aqueous composition of the present invention generally contains from about 0.1 to about 5%, preferably from about 0.25 to about 3%, and more preferably from about 0.5 to about 1.5% by weight of amine oxide, based upon 100% total weight of wood preservative composition. For application to pressure treated wood, the composition preferably contains from about 0.1 to about 5% and more preferably from about 0.25 to about 3% by weight of amine oxide, based upon 100% total weight of wood preservative composition. For controlling sapstain, the wood preservative composition preferably contains from about 0.1 to about 5% and more preferably from about 0.5 to about 1% by weight of amine oxide, based upon 100% total weight of wood preservative composition.
According to a preferred embodiment, the wood preservative composition comprises a waterproofing and biocidally, fungicidally, or sapstain inhibiting effective amount of one or more amine oxides.
The wood preservative composition of the present invention may further comprise a solvent, such as water, a water miscible solvent, or a combination thereof. Suitable water miscible solvents include, but are not limited to, alcohols, glycols, esters, ethers, polyethers, amines, ketones, and any combination of any of the foregoing. Preferably, the solvent is water.
The wood preservative composition may also comprise further auxiliaries, such as corrosion inhibitors, iron stain inhibitors, wetting agents, adhesives, emulsifiers, fillers, carriers, viscosity and pH regulators, binders, tackifiers, other active ingredients (such as other biocidally active ingredients), and any combination of any of the foregoing.
Suitable iron stain inhibitors include, but are not limited to, phosphonic iron stain inhibitors, such as aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, diethylenetriaminepenta(methylenephosphonic acid), bis-(hexamethylene)triamine phosphonic acid, and any combination of any of the foregoing. The inventors have discovered that the inclusion of a phosphonic iron stain inhibitor, such as 1-hydroxyethylidene-1,1-diphosphonic acid and bis-(hexamethylene)triamine phosphonic acid, improves the biological efficacy of the amine oxide. Furthermore, since many iron stain inhibitors are highly acidic, prior art treating solutions containing them typically have a pH of less than 2. In contrast, wood preservative compositions of the present invention which contain iron stain inhibitors typically have a pH ranging from about 3 to about 7.
Other adjuvants may be included in the composition as known to one of ordinary skill in the art.
Generally, the wood preservative composition is neutral, i.e., has a pH of from about 6 to about 8.
According to a preferred embodiment, the wood preservative composition is substantially free (i.e., contains less than 0.1% by weight) of quaternary ammonium compounds, halogenated compounds (including halides and chlorinated compounds such as chlorophenols), or both. More preferably, the wood preservative composition contains less than 0.01, 0.001, or 0.0001% by weight of quaternary ammonium compounds, halogenated compounds (including chlorine containing compounds such as chlorophenols), or both. Most preferably, the wood preservative composition is free of quaternary ammonium compounds, halogenated compounds (including chlorine containing compounds such as chlorophenols), or both.
According to another preferred embodiment, the wood preservative composition is substantially free (i.e., contains less than 0.1% by weight) of biocides, bactericides, or fungicides other than amine oxides. More preferably, the wood preservative composition contains less than 0.01, 0.001, or 0.0001% by weight of biocides, bactericides, or fungicides other than amine oxides. Most preferably, the wood preservative composition is free of biocides, bactericides, or fungicides other than amine oxides.
A particularly preferable sapstain inhibiting composition of the present invention comprises cocodimethylamine oxide and, optionally, an iron stain inhibitor. Also, special mention is made of cocodimethylamine oxide alone or in combination with hexadecyldimethylamine oxide as a preservative for use in pressure treating lumber.
The wood preservative composition may be applied to any wood substrate, such as any hard wood or soft wood, to present sapstain. Typically, for preventing or controlling sapstain and mold, the wood preservative composition is applied to green wood. The term xe2x80x9cgreenxe2x80x9d as used herein is defined as freshly cut, unseasoned, or the like. Examples of suitable wood substrates include, but are not limited to, maple, oak, birch, cherry, fir, and the like. The wood preservative composition may be applied to any wood substrate which is to be pressure treated. Preferably, the wood substrate is a soft wood, such as a pine, fir, or hemlock. Suitable pine wood substrates include, but are not limited to, southern yellow pine and ponderosa pine. More, preferably, the wood substrate is southern yellow pine.
Methods of applying the wood preservative composition include, but are not limited to, spraying, soaking, immersing, vacuum impregnation, pressure treatment, brushing, and the like. Preferably, the substrate is immersed in the wood preservative composition of the present invention or the substrate is pressure treated with the composition.
The composition may be prepared by dissolving the amine oxide and adjuvants in water. The mixture may be heated to a temperature of from about 50 to about 60xc2x0 C. and/or stirred to expedite mixing. For example, a 30% (w/w) mixture of hexadecyl dimethyl amine oxide, available as Barlox(copyright) 16S from Lonza Inc. of Fair Lawn, N.J., which is a paste, may be mixed with a 30% (w/w) aqueous solution of coco-dimethylamine oxide and water to form a concentrated solution suitable for producing use dilutions of the wood preservative composition.
A wood substrate containing the wood preservative composition generally comprises from about 0.1 to about 5% by weight, preferably from about 0.25 to about 3% by weight, and more preferably from about 0.5 to about 2% by weight of amine oxide, based upon 100% total weight of preserved wood substrate.
Another embodiment is a method of controlling microorganisms, such as fungi and sapstain organisms, on and/or in a wood substrate comprising applying a biocidally effective amount of the wood preservative composition of the present invention to the wood substrate. The term xe2x80x9ccontrollingxe2x80x9d as used herein includes, but is not limited to, inhibiting the growth of microorganisms, such as fungi and sapstain organisms. Non-limiting examples of fungi are Trametes versicolor (T. versicolor),Gloeophyllum trabeum (G. trabeum), Poria placenta (P. placenta), Lentinus lepideus (L. lepideus), Coniophoraputeana (C. puteana), and Chaetomium globsum (C. globsum).
According to a preferred embodiment, the wood preservative composition further comprises one or more iron stain inhibitors, preferably phosphonic iron stain inhibitors, is applied to a wood substrate to control sapstain organisms. Generally, the composition contains from about 0.05 to about 1% by weight of phosphonic iron stain inhibitor, based upon 100% by weight of composition. Preferably, the composition contains from about 0.1 to about 0.5 and more preferably from about 0.15 to about 0.3% by weight of phosphonic iron stain inhibitor, based upon 100% by weight of composition.
The following examples illustrate the invention without limitation. All parts and percentages are given by weight unless otherwise indicated. All Barlox(copyright) ingredients are available from Lonza Inc. of Fair Lawn, N.J.